Adoptive immunotherapy for cancer: building on success. Substantial progress has been made in our understanding of the molecular and cellular bases of T cell mediated anti-tumor responses. T cells are potent effectors of the adaptive anti-tumor immune response. Some target antigens recognized by tumor-reactive CD8+ T cells are mutated antigens. The molecular signals that modulate T cell activation, function and memory are being elucidated. Both positive and negative signals from co-stimulatory molecules have been shown to shape the anti-tumor response. Cytokines, including those with receptors that contain the common cytokine-receptor gamma chain have been shown to alter the programming of effector CD8+ T cells.